What is a Vertebrate

1
What is a Vertebrate?

• Vertebrate Anatomy Unit 1

2
FIRST A Vertebrate is an ANIMAL

• What is an Animal?
• KINGDOM Level of Taxonomy
• Includes all organisms that possess the following
  characteristics
• Multicellular
• Heterotrophic
• No cell walls around cells
• Several other characteristics

3
SECOND A Vertebrate is a CHORDATE

• What is a Chordate?
• PHYLUM level of Taxonomy
• Includes all ANIMALS that possess the following
  characteristics
• Dorsal Hollow Nerve Cord
• Pharyngeal Gill Slits
• Notochord
• Post-anal Tail
• A few chordates possess ALL these characteristics
  at all life stages, but most only possess all of
  these during EMBRYONIC stages.

4
THIRD A Vertebrate is a VERTEBRATE

• What is a VERTEBRATE?
• SUBPHYLUM level of Taxonomy
• A level not normally addressed in intro bio
  classes
• Includes all CHORDATES that possess the following
  characteristics
• A BACKBONE that protects the nerve cord and
  supports the body replaces the notochord
• This also generally implies the presence of a
  cranium (skull) to protect the brain.
• Some animals have ONLY the cranium, thus they are
  not quite true vertebrates

5
TRUE or FALSE?

• All CHORDATES are VERTEBRATES.
• All VERTEBRATES are CHORDATES.

6
The term Chordata comes from

• The Notochord

7
About the Notochord

• In a Vertebrate Chordate,
• the Notochord is present only during the
  EMBRYONIC stages of life.
• The notochord is replaced by the backbone

8
About the Nerve Cord

• Dorsal
• Hollow
• Anterior end enlarged to create the BRAIN

9
Pharyngeal Gill Slits

• Pharynx throat
• Present in embryos
• These slits in the throat area become the gills
  in fish and other vertebrates that breath water
• In mammals and other land vertebrates they become
  structures of the lower jaw, face and throat.

10
(No Transcript)
11
Other Chordate Characteristics

• Closed circulatory system
• Blood always contained in blood vessels
• Muscle blocks or segments called somites in
  embryos

12
Who are the Chordates closest relatives?

• The closest INVERTEBRATE relative of the
  chordates are the members of Phylum Echinodermata
• The Sea Stars
• The Sea Urchins
• The Sea Cucumbers
• How can this be?
• The embryonic development of echinoderms has a
  very important similarity to the embryonic
  development of chordates, even though the adult
  forms look very different.

13
Echinoderms and Chordates

• The embryonic opening called a blastopore becomes
  an ANUS in both echinoderms and chordates.
• In all other INVERTEBRATES it becomes the MOUTH.

14
Phylum Chordata 4 subphyla

• Subphylum Urochordata
• Subphylum Cephalochordata
• Subphylum Myxini
• Subphylum Vertebrata

15
Subphylum Urochordata

• The Tunicates
• Also called Sea Squirts
• The 4 Chordate characteristics are present in the
  larval form
• The adult looks very different
• Larva are free swimming with tails, etc.
• Adult is sessile.

16
(No Transcript)
17
Phylum Cephalorchordata

• A group called the lancelets
• Most common member of this group is amphioxus
• Swimmers
• Possess all chordate characteristics in adult
  form

18
(No Transcript)
19
Phylum Myxini

• New Phylum
• Once thought to be vertebrates, but they do not
  possess a true backbone only a true cranium
• Hagfish is the only member

20
Subphylum Vertebrata

• WE are vertebrates hence humans have studied
  phylum vertebrata a lot.

21
When did the 1st vertebrates arise on Earth?

• Around 500 million years ago

22
What were the first vertebrates like?

• The first vertebrates were DIFFERENT from
  vertebrates we know today.
• They lacked JAWS.
• Think hagfish and lampreys which are the only
  chordates/vertebrates that remain today who lack
  jaws.
• Jawed vertebrates did not appear until around 400
  million year ago

23
Where did vertebrates first evolve?

• Ocean

24
Defining characteristic of a vertebrate?

• Backbone
• Though others are discussed.

25
Vertebrates and sex

• All vertebrates have separate sexes male and
  female

26
Some terms with regard to reproduction

• Oviparous
• Egg layer
• Young are nourished from yolk inside an egg that
  is laid outside the mothers body

27
Some terms with regard to reproduction

• Ovoviparous
• Young develop internally, but are nourished with
  YOLK as though they were inside an egg.
• Live birth

28
Some terms with regard to reproduction

• Viviparous
• Young develop internally
• Nourished directly from the mothers bloodstream
• NO yolk
• Placenta and umbilical cord involved